1. Field of the Invention
The present invention relates to a semiconductor device and the manufacturing method thereof, and more particularly to a resin-sealed-type semiconductor device in which a semiconductor chip, having a moving section, is packaged, and the manufacturing method of such semiconductor device.
2. Description of the Related Art
A technology for manufacturing a several hundred μm level micro-structure using micro-machining technology, which relies upon semiconductor micro-processing technology, is developing. For example, such technology is already applied to various sensors, to optical switches in the optical communications field and to radio frequency (RF) components.
A certain micro structure having a moving section can be manufactured by a conventional semiconductor manufacturing process so that such micro-structure can be integrated on a single chip along with transistors.
A chip on which a system with specific functions, including the micro-moving structure having a moving section, is called a Micro-Electrical-Mechanical-System (MEMS) chip, or a Micro-System Technology (MIST) chip. Such chip is hereafter simply called an MEMS chip in this specification. One example of the MEMS chip is an acceleration sensor chip. The MEMS chip is packaged into a device that includes a control chip for controlling the MEMS chip.
A conventional semiconductor acceleration sensor (package) which prevents the breakdown of an acceleration sensor chip (i.e., MEMS device) even if excessive acceleration is received is disclosed in Japanese Patent Application Kokai (Laid-Open) No. 6-242141. This conventional semiconductor acceleration sensor can have a good manufacturing yield.
The semiconductor acceleration sensor disclosed in Japanese Patent Application Kokai No. 6-242141 includes an acceleration sensor chip, an IC chip mounted on the top face of the acceleration sensor chip, and a substrate on which these chips are mounted.
The IC chip is mounted such that the cavity covers and protects the moving section of the acceleration sensor chip. A processing circuit for processing the output signal of the acceleration sensor chip is formed on the IC chip, and the cavity is formed in the back face of the IC chip. The substrate on which the IC chip and acceleration sensor chip are mounted is contained in an air-tight space formed by a base and a box-shaped cap.
In this conventional acceleration sensor chip package, the IC chip is layered on the acceleration sensor chip. The IC chip and acceleration sensor chip are contained in the air-tight space defined by the base and the box-shaped cap.
The moving section has a weight section and the beam section which supports the weight section. Recently the sizes of acceleration sensor chips are decreasing. So implementing both downsizing and an improvement of sensitivity is demanded, but the downsizing of the moving section has limitations. Therefore the downsizing of an acceleration sensor chip depends on downsizing the frame enclosing this moving section.
The conventional acceleration sensor chip package has the IC chip on the acceleration sensor chip. As the size of the frame section of acceleration sensor chips decreases, it is becoming difficult to layer the IC chip on the acceleration sensor chip, without damaging the functions of the acceleration sensor chip.
Also in the conventional configuration, resin sealing cannot be used. Thus, the acceleration sensor chip is sealed using a cap, which makes the entire package bulky.
The package having the layered chips together with the cap requires a precise alignment of the chips. This makes manufacturing steps complicated, and decreases the mass producability of the package, which in turn increases manufacturing cost.
Accordingly, a technology to further decrease the size and manufacturing cost of a semiconductor device (e.g., acceleration sensor chip package) is demanded.